Power tools may be of different types depending on the type of output provided by the power tool. Power tools such as drills, hammers, grinders, impact wrenches, circular saws, reciprocating saws, and so on are marketed in different parts of the world and used widely in consumer, DIY, and construction market. Power tools may be provided with a rotary motor such as a brushless DC (BLDC) motor.
Conventionally, large power tools that require high power for heavy duty applications may be powered by an alternating current (AC) power source, while other portable power tools may be powered by a direct current (DC) power source such as a battery pack. More recently, power tools that were conventionally powered by AC power sources only have been provided with the capability to receive AC or DC power supplies. U.S. Pat. No. 9,406,915, filed May 18, 2015, which incorporated herein by reference in its entirety, provides examples of AC/DC power tools that can be powered by an AC power supply, a DC power supply, or a hybrid combination of AC and DC power supplies.
Power tools including BLDC motors typically include an inverter circuit including a series of semiconductor solid-state switches that drive the different phases of the motor. The type of switches employed in such circuits are selected based on the power output requirements.
BLDC motors may also be wound differently based on the power output requirements. The two basic winding configurations for the phases of the motor are wye and delta connections. A motor with windings configured in the delta configuration can operate at a greater speed than the same windings configured in the wye configuration. A motor with windings configured in the wye configuration can operate with a greater torque than the same windings configured in the delta configuration.
Furthermore, the windings within each phase of the motor may be connected in either series or parallel. A series connection is often more suitable for relatively high voltage applications, and a parallel connection is often more suitable for relatively low voltage applications.
What is needed is a system that can utilize proper inverter switches for the needed application without sacrificing performance. What is further needed is a system that can configure the motor in the most effective manner based on the power requirements of the power tool to increase motor efficiency.
The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.